A conventional switch device, especially for those switches using bi-metallic plate to prevent from being burn when an overload is happened, generally includes a bi-metallic plate which is deformed under overload conditions so as to separate the two contact points respectively located on the bi-metallic plate and one of the two terminals. Some inherent shortcomings for these conventional safety switch devices are found. There are too many parts involved in the safety switch device and a longer period of time is required when assembling the switch device, this increases the cost of the products. The parts might be arranged inaccurately and affects the deformation of the bi-metallic plate. Once the bi-metallic plate is deformed to cut off the circuit, because of the improper arrangement of the parts as mentioned above, the bi-metallic plate could deform to re-connect the two contact points to connect the circuit again. Because the inaccuracy of the deformation of the bi-metallic plate, the switch member does not set the “OFF” position after the bi-metallic plate is deformed to cut off the circuit.
Therefore, it is desired to have a device to ensure that the bi-metallic plate has proper flexibility and is deformed to accurately separate the two contact points and to pivot the switch member to “OFF” position.